Work on the isolation of the C. briggsae growth requirement from soypeptone will be continued. A biologically active preparation, consisting of di- or tripeptides has been further fractionated on Dowex-50 using a pyridine-acetic acid gradient. These fractions will be tested, using as the criterion for nutrient activity, the ability to support continued subculture of the organisms in the basal medium plus sterols and myoglobin. Work will continue on the mechanisms of the glycerol vs. glucose excretion in free-living nematodes. The former compound is excreted when the organisms are in "whole medium," and the latter in buffer solution. The following approach will be made. After feeding acetate-C14 to C. briggsae under both sets of conditions, sugar phosphates will be isolated to determine at what stage the glucose synthetic pathway fails. Enzymes in this metabolic area will be compared for activity (or lack of activity) in organisms from "whole medium" and from buffer. Investigations will be made to discover if the process involves enzyme inhibition, induction or removal.